Introduction: There has been an increased interest in the role of preoperative posterior tilt, as measured on lateral radiographs, on the outcomes of internal fixation of non-displaced femoral neck fractures (FNF). The goal was to assess the available evidence for this in the literature.
Patients and methods: PRISMA guidelines were followed. PubMed, Embase and Cochrane were searched on June 10th, 2020 for studies assessing the role of posterior tilt on outcomes of internal fixation of non-displaced FNF. Primary outcomes were non-union and fixation failure, avascular necrosis (AVN), treatment failure, and reoperation (excluding symptomatic hardware removal). Outcomes were reported in Odds Ratio (OR) with 95% confidence intervals [CI].
Results: Fourteen studies and 3729 patients were included (mean age 76 years, 72% female, mean follow-up 25 months). Moderate evidence was noted for the following: patients with greater preoperative posterior tilt had an increased risk of non-union and fixation failure (OR 2.4 [1.3 - 4.3]; p = 0.006), no increased risk of AVN (p = 0.550), an increased risk of treatment failure (OR 6.0 [2.2 - 15.9]; p<0.001) and reoperation (OR 2.5 [1.4 - 4.4]; p = 0.002). Furthermore, a greater preoperative tilt of 9.0° [4.1° - 13.9°] for treatment failure and 6.1° [3.7° - 8.5°] (p<0.001) for reoperation were noted in the unsuccessfully treated groups when compared to the successfully treated groups. Four studies found a threshold for posterior tilt ranging from 7° to 20° CONCLUSION: There is moderate evidence that patients with non-displaced FNF and greater tilt have an increased risk of unsuccessful outcomes following internal fixation. Older patients with a preoperative tilt of ≥20° might benefit from arthroplasty surgery, although studies assessing the optimal threshold are needed.
Keywords: Avascular necrosis; Failure; Fracture displacement; Hip fractures; Internal fixation; Posterior tilt.
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